Relational join is a common operation in complex query processing in DBMS. Equijoin is a frequently used type of relational join. Equijoin may be implemented using a number of different algorithms. Hash-join is one of the most efficient and commonly applied algorithms for equijoin. Hash-join is a highly parallel algorithm, and may be implemented in part using software and/or hardware.
Modern databases, such as those used for processing business data, typically must handle large numbers of complex queries. Business data in these databases may comprise information relating to customers, products, orders, employees, etc. Complex queries of such business data can be computationally expensive. For example, queries relating to a particular customer's order history or purchased products or queries relating to which employees processed a particular order, may need to be performed continuously. Such complex queries may seek information which is contained in more than one table of a database. In such cases, relational join operations are performed to handle the query. The amount of business data which is queried can lead to computationally expensive relational join operations.